收获时期及干燥方式对花生品质的影响

为探索不同收获期和后熟干燥方式对花生品质的影响,该研究以泰花5号花生为试验对象,采用在株晾干法、鲜摘晾干法、鲜摘催干法3种方法对3个时期收获的花生进行后熟干燥品质对比测试分析。结果表明,在同一收获期中,在株晾干法花生百果质量、百仁质量显著高于其他2种方法,该后熟干燥方法的增重作用随收获期提前而更明显(P0.05);但在相同后熟干燥方法中,提前2周收获的干燥荚果百果质量、百仁质量均显著低于前1周和原定收期收获的花生荚果(P0.05)。自然晾晒干燥期间,在株晾干花生果壳、果仁含水率均高于同期鲜摘晾干果壳、果仁含水率,两种晾干方式含水率差异在初期逐渐增加、随后逐渐减小直至达到相当的最终含水率。鲜摘晾干和鲜摘催干果仁粗蛋白、粗脂肪均未见显著差异(P0.05),而在株晾干果仁粗蛋白、粗脂肪含量分别增加了3%、2%左右;而收获期越早,果仁粗蛋白和粗脂肪含量越低。在果仁不饱和脂肪酸总相对含量上,鲜摘晾干、在株晾干果仁与新鲜果仁未见差异(P0.05),但机械催干果仁显著低于新鲜果仁(P0.05)。在果仁氨基酸组成方面,经3种不同后熟干燥方法后,8种主要氨基酸及氨基酸总含量均呈现在株晾干含量最高、鲜摘晾干其次、机械催干最低的差异(P0.05)。在株晾干花生果柄横断面显微结构观察表明,果柄在干燥初期仍保留对水分、养分等物质输导、贮藏的空间通道,为荚果的物质代谢和积累提供必要条件。该研究结果为花生生产实践提供参考。

Effects of different harvesting dates and drying methods on peanut quality

Abstract: Peanut is viewed as one of the most important oil crops and food protein resources in China. Its production and planting area have been ranked the first and second in the world, respectively. The post-harvest drying of peanut is an indispensable process in its produce system. It is an important task to determine when to harvest and how to dry peanuts in practice, which will affect the final quality of peanut products. In order to investigate the effects of different harvesting dates and post-ripening drying methods on the quality of peanut, 3 drying modes including sun-drying of pods on plants, sun-drying of picked pods and air-drying of picked pods were adopted for Taihua-5 peanuts which were harvested on the original harvesting date, 1 week earlier and 2 weeks earlier, respectively, and the peanut qualities were analyzed. The results showed that hundred-pod weight and hundred-kernel weight of dried peanuts with the method of sun-drying of picked pods on plants were both higher than the other 2 methods, and the weight-increasing effect was more obvious for earlier harvesting date (P<0.05). As far as the same post-ripening drying method was concerned, hundred-pod weight and hundred-kernel weight of dried peanuts harvested 2 weeks earlier were significantly lower than the one week earlier and the original harvesting date (P<0.05). During the sun-drying period, the water content of peanut shells and kernels with the method of sun-drying of pods on plants were significantly higher than that with the method of sun-drying of picked pods. The difference in water content between the 2 methods was increased in the early stage of drying, and then gradually decreased until almost the same final moisture content was reached (P<0.05). No significant difference was observed for both crude protein content and crude fat content of dried kernels between the 2 methods of sun-drying of picked pods and air-drying of picked pods (P>0.05). However, the 2 indicators under the method of sun-drying of pods on plants were increased by 3% and 2%, respectively. The earlier the harvest date, the lower the crude protein and crude fat content. There was no significant difference in the total relative content of unsaturated fatty acids in the fresh-harvested kernels, dried kernels with sun-drying of pods on plants and dried kernels with sun-drying of picked pods (P>0.05), however, that indicator with the method of air-drying of picked pods was significantly higher than the fresh-harvested kernels (P<0.05). The contents of 8 major amino acids and the total amino acids content in peanut kernels with 3 post-ripening drying methods were ranked in descending order as sun-drying of pods on plants, sun-drying of picked pods and air-drying of picked pods (P<0.05). Electron microscopy photos of cross section of peanut pedicel with the method of sun-drying of pods on plants indicated that the peanut pedicel remained the channel space for the transportation and storage of water and nutrients in the early stage of drying, which provided the necessary conditions for the metabolism and accumulation of peanut pods. The results of the study can provide reference for peanut production practice.